EXAMPLE 2 mv/s UME'S in sol-gels Q: Identify the waves in the cvs shown at left op: UME-slow scan rate(sigmoidal shape 600500400300200100 Bottom: UME-fast E mV Figure 4. Cyclic voltammograms of gel-encapsulated Fccoo scan rate (initially 3 mM) acquired 1(dotted line). 2 (solid line), and 26(dashed Annette R. Howells, Pedro J. Zambrano, and Maryanne M line)days after gelation Collinson" Diffusion of Redox Probes in Hydrated Sol-Gel- 0;72(21);5265
EXAMPLE: UME’s in Sol-Gels Q: Identify the waves in the CV’s shown at left Top: UME - slow scan rate (sigmoidal shape) Bottom: UME - fast scan rate Annette R. Howells, Pedro J. Zambrano, and Maryanne M. Collinson* ; Diffusion of Redox Probes in Hydrated Sol-GelDerived Glasses, Analytical Chemistry; 2000; 72(21); 5265-5271
UMES Fast scan rates Slow scan rates 30V/s 5 mvs planar diffusion radial diffusion 口■ 0.1um 0.1um
UME’s: 0.1 m Fe3+ Fast scan rates 30 V/s planar diffusion Slow scan rates 5 mV/s radial diffusion 0.1 m
UME'S Radial vs. planar Diffusion Radial Diffusion Planar Diffusion Redox wave Redox wave sIgmoIdal shape normal shape Iss=4nFrD Co 人V 112 d Do D1/2C ss scan rate independent∝D。C
UME’s Radial vs. Planar Diffusion Radial Diffusion Redox wave: – sigmoidal shape Iss = 4nFrDoCo * – Iss scan rate independent DoCo * Planar Diffusion Redox wave: – normal shape Ip 1/2 Do 1/2 C
EXAMPLE 2 mv/s UMES in Sol-gels Learn d。 from ca ob tain c from slow 0 scan rate cv (ss) s 600500400300200100 E mV Figure 4. Cyclic voltammograms of gel-encapsulated Fccoo (initially 3 mM) acquired 1(dotted line). 2 (solid line), and 26(dashed Annette R. Howells, Pedro J. Zambrano, and Maryanne M line)days after gelation Collinson" Diffusion of Redox Probes in Hydrated Sol-Gel- 0;72(21);5265
EXAMPLE: UME’s in Sol-Gels Learn Do from CA Obtain Co * from slow scan rate CV (Iss) Annette R. Howells, Pedro J. Zambrano, and Maryanne M. Collinson* ; Diffusion of Redox Probes in Hydrated Sol-GelDerived Glasses, Analytical Chemistry; 2000; 72(21); 5265-5271
20 mV/s EXAMPLE 2: Look Ma. no electrolyte Expenment 10 20 mv/ 了 [S2 MO180621 [S2Mo18062I 5-+e Emerin Emulsion [S2 Mo18062]6 1100mV/s 10 BAS 100-A 10 z9 Expenment 3-electrode cell 1000800600400-200 GC macrodisk/Pt wire/Pt Potential (mv) vs Pt wire Alan M. Bond, Darren C Coomber, Stephen w Feldberg, Keith B Oldham, and Truc Vu; Analytical aCn with no electrolyte Chemistry;200l;73(2);352-359
EXAMPLE 2: Look Ma, No Electrolyte! [S2Mo18O62] 4- + e- = [S2Mo18O62] 5- + e- = [S2Mo18O62] 6- BAS 100-A 3-electrode cell: – GC macrodisk/Pt wire/ Pt wire – ACN with no electrolyte Alan M. Bond,* Darren C. Coomber, Stephen W. Feldberg, Keith B. Oldham, and Truc Vu ; Analytical Chemistry; 2001; 73(2); 352-359. 20 mV/s 20 mV/s 100 mV/s